Attenuation and sensitivity to heat (or thermal) aging may be critical attributes of optical fibers, particularly for high data rate optical fibers. In making optical fibers, it may be necessary or desirable to minimize attenuation loss in the intended window of operation for the fiber. Attenuation in an optical fiber can increase after fabrication of the fiber because of a phenomenon called “heat aging.” Heat aging is the tendency of some optical fibers to increase in attenuation over time following formation of the fibers due to temperature fluctuations in the fiber's environment. Typically, the attenuation change from heat aging may be apparent at approximately 1200 nanometers (nm) with increasing effect up to about 1700 nm in a spectral attenuation plot. Furthermore, attenuation may be the result of Rayleigh scattering loss. Therefore, improved methods that reduce fiber attenuation due to heat aging and Rayleigh scattering are desired.